Larval Deer Ticks Can Transmit Borrelia miyamotoi
Borrelia miyamotoi transovarial transmission means larval deer ticks can be infected at birth—making them a previously underrecognized risk.
Unlike Lyme disease, where larval ticks are typically not infected, Borrelia miyamotoi can be passed from adult ticks to their offspring through transovarial transmission.
This means larvae may already carry infection when they hatch.
CDC Study on Transovarial Transmission
Researchers from the CDC demonstrated that larval ticks infected with B. miyamotoi can transmit the infection during feeding.
In experimental models, “minimal or partial blood meals by transovarially infected larvae resulted in approximately half of hosts developing detectable infection,” writes Breuner.
This finding challenges the assumption that larval ticks are harmless.
Why Larval Ticks Pose a Unique Risk
In Lyme disease, larval ticks are not typically infected because Borrelia burgdorferi is not transmitted through eggs.
In contrast, B. miyamotoi can be transmitted from mother to offspring, allowing larvae to spread infection.
This distinction has important implications for both prevention and diagnosis of tick-borne diseases.
Public Health Implications
Larval ticks are most active in July and August—a time when people may be less vigilant about tick protection.
Public health messaging has traditionally focused on nymphal ticks in spring and early summer, but this research suggests that late summer exposure also carries risk.
Tick prevention strategies should include awareness of larval ticks and their seasonal activity.
Clinical Perspective
Clinicians should consider Borrelia miyamotoi infection in patients with tick exposure during summer months—even when exposure to nymphal ticks seems unlikely.
Failure to recognize larval transmission may contribute to missed or delayed diagnosis.
Clinical Takeaway
Larval deer ticks can transmit Borrelia miyamotoi, expanding the seasonal and clinical risk of tick-borne infections.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
Lone Stars also transmit some infections transovarially.
So if you have had chiggers could you have lyme or another tick borne illness?
No. I posted an story about the association of a chigger bite with alpha-gal allergy (red meat allergy). These stories will hopefully trigger further research. You can read the story I posted at https://www.facebook.com/plugins/post.php?href=https%3A%2F%2Fwww.facebook.com%2Fdanielcameronmd%2Fposts%2F2204587233160186
Hi Dr. Cameron, I know this article is from a few years back, but thought I’d try my luck in getting in touch with you! Do you know what percentage of larval ticks are suspected of being infected with borrelia miyamotoi in states like CT? Thank you!
I have not seen any information on how often Larval ticks harbor B. miyamotoi or B. burgdorferi.
Thank you!
Hi Dr Cameron,
Can a larvae deer tick transmit Lyme disease to a human? Thanks so much
Transovarially transmission has been considered in tick borne disease, that is the infection passes through the egg to the larva. I have not seen much research in this area.
Hi Dr. Cameron,
I believe I have been bitten by a larval deer tick. (viewed under microscope, six legs, all mouth “prongs” intact. I recently finished a two week course of Doxycycline for an infected lone star tick bite. I removed the larval tick two days ago, and I believe I caught it well less than 24 hours after attaching, though I can’t be sure. I was given Doxycyline from my dermatologist for prophylaxis. He said I should take one 100mg pill. Do you think this is necessary for a larval tick bite that is not infected, or is this not enough and I should look into another full course of Doxy? Obviously I need to do a better job protecting myself in the future. Thanks in advance.
The prophylaxis dose should have been 200 or two 100 tablets. I am not supportive of a single dose prophylaxis approach. Read my perspective.vv https://danielcameronmd.com/perspective-dont-trust-single-dose-doxycycline-to-prevent-lyme-disease/
There has been no study of prophylaxis for a larval tick.
Thank you, I chose not to take the medication in this case. I did not identify the tick properly, either. Upon turning it over and looking closer, I actually think it may be a nymph, unfortunately. Either a lone star or deer tick nymph. I am caring for the bite site carefully, and have chosen to do “watchful waiting.” I have no idea if I’m doing the right thing. I don’t know if jumping into another several weeks of Doxycyline therapy after just completing two weeks is a good idea, either. I am located in central NC.